FIG. 1A shows an example vehicle 100 having a suspension system using shock absorbers (e.g., telescopic dampers) 110. The shock absorbers 110 regulate suspension movement and help to maintain the wheels 120 in contact with the ground at all times, as well as to reduce bounce, roll and sway. The shock absorbers 110 also help to reduce brake dive, acceleration squat and to dampen or isolate road induced disturbances having a low frequency (e.g., between about 0 Hz-30 Hz) and a high amplitude. Conventional shock absorbers isolate vibrations related to vehicle wheel and body excitation inputs in the range of about 5-14 Hz, with higher frequency excitation inputs having smaller amplitudes being transmitted to the vehicle structure.
In various suspension system configurations, the shock absorbers 110 may be integrated with struts and coils (e.g., MacPherson struts in a MacPherson front suspension, etc.) or may be provided separately thereto (e.g., coil spring suspension system). For example, in coil spring suspension systems, the shock absorber is connected at a first end to the chassis or frame and at another end to the upper control arm (e.g., short-arm) or the lower control arm (e.g., long-arm), which are connected to a wheel hub via wheel spindles and ball joints. A coil spring works against one of the control arms (e.g., lower control arm for Type 1 Coil Spring or double wishbone suspension, upper control arm for Type 2 Coil Spring) to support the weight of the vehicle via a ball joint (e.g., via the lower ball joint in the Type 1 Coil Spring or via the upper ball joint in the Type 2 Coil Spring), and the shock absorber controls spring oscillations. In MacPherson strut suspensions, the upper control arm is omitted. A strut assembly including a strut, spring and shock absorber is disposed to connect the shock absorber, at a first end, to the chassis or frame and, at the other end, to a ball joint at the lower control arm. In a MacPherson strut suspension, the strut bears the load of the vehicle weight.
Shock absorbers 110 are conventionally selected to provide a desired response (e.g., compression and rebound performance) and balance to address primary ride perturbations affecting rigid body motion of the passenger compartment relative to the road, arising from high-amplitude, low-frequency events, such as potholes and speed bumps. Shock absorbers 110 are not conventionally tuned to address secondary ride perturbations having a low amplitude and a high frequency (e.g., road noise).
FIG. 1B shows an example truck 130 using shock absorbers 140 as steering stabilizers or steering dampers. Shock absorbers 140 help dampen lateral or side-to-side movement in a vehicle's suspension to reduce vibration, steering wobble or shimmy and bump steer and to make heavier vehicles (e.g., trucks, RV's, etc.) easier to drive over rough terrain as well as at highway speeds, particularly if the vehicle is heavily laden or towing a load.
FIG. 2 shows a hydraulic engine mount (HEM) 200, which is disposed between an engine and a frame of a vehicle to isolate vibration from the engine and reduce the engine vibration felt inside the vehicle. The HEM 200 is mounted to the engine through the top mounting studs 201 and to the frame through the bottom mounting studs 202. The HEM 200 includes metal inserts 203, 204 to support the forces and torques generated by the engine and an elastomeric element 205 or matrix to dampen vibrations and enable compression and shear displacement or elastic deformation. The upper chamber 207 and a lower chamber 208 are filled with an operating fluid comprising a mixture of ethylene glycol (anti-freeze) and distilled water. Upon compression of the upper chamber 207, the operating fluid is forced to flow through fluid pathways in an orifice plate 211. A first fluid pathway is formed by inertia tracks 212, which are long channels having a small cross-sectional area to provide a high level of fluid damping or resistance to fluid flow to control, for example, engine resonances. A second fluid pathway is formed by a decoupler 213, a free-floating, thin disk disposed in the orifice plate 211 to move between a top portion and a bottom portion of the orifice plate 211 and to occlude orifices 214 in the orifice plate 211 at those positions. The orifice plate 211 positioned between the upper chamber 207 and lower chamber 208 controls the fluid system characteristics. Minor changes in the geometry and flow conditions of the orifice plate 211 can significantly influence dynamic behavior. A flexible diaphragm 215 functions as an accumulator as the fluid flows from the upper chamber 207 to the lower chamber 208. A vent 216 allows air to escape from a base plate 217 responsive to movement of the flexible diaphragm 215.